Some light on the dashboard regarding engine

https://www.onlymanuals.com/hyundai/other_model/hyundai_diesel_engine_d4ea_workshop_manual_pdf

No. Make sure it lines back up. Some vehicles are two revolutions of the crank to one rev for the cam/s. Some are four rev to one. If they don't line up. Reset the timing. If it doesn't line up, At best it won't start. At worse you could trash the engine,Interference engine. Some engines go off the chain. It could take up to 32 revolutions to bring the marks back in line.

Not related , check for leaks on engine = water , could be leaking from pump flange

2006 xtrail was overfilled with oil now oil light is coming on and am getting a noise from engine. Help

how do i change a diesel pump on a sprinter bus

A non working fuel pump in those early year Grand Cherokees is usually either a bad pump or an ecu in need of repair. Make sure that the check engine light comes on, on the dashboard, when you turn the key to on. If that check engine light does not come on, the ecu is bad. If it does come on, more than not the fuel pump is shot and will have to be replaced.

Where is the fuel pump located on the Honda civic 1.8 Vti 5 door car?

As the engine temp increases, oil returns to the sump (pump location) faster. You may just be low on oil. When its cold, the light is on at times...

Your oil becomes too fluid as the engine gets warmer. When the engine rotates slower at stops, the oil pump won't make pressure. At speeds, more oil is pumped and the pressure rises.
Have you recently changed your oil? Or maybe is too old. The real problem would be if you read zero at normal cruising revolutions.